1. Field of the Invention
The present invention generally relates to internal combustion engines having reciprocating pistons. More specifically, this invention relates to an internal combustion engine having separately designated combustion and exhaust cylinders through which a two-stage exhaust system is implemented for deriving work from the combustion gases of the combustion cylinders.
2. Description of the Prior Art
Internal combustion (IC) engines currently are by far the predominant engine form used today for purposes of providing power to propel motorized vehicles, as well as many other forms of transportation and recreation devices. The IC engine is preferred, for its exceptional power and weight ratio and energy storage potential (miles traveled between refueling), when compared to other comparable forms of automotive power. However, concern for the environment and for preservation of natural resources has continuously encouraged efforts to improve the efficiency, performance and fuel economy of IC engines while reducing their noxious emissions and noise.
Various arrangements have been suggested to improve the combustion efficiency of IC engines by providing engines with intercooperating cylinders having different designated functions. One example of this in U.S. Pat. No. 4,715,326 to Thring. Thring discloses pairs of cylinders in which the first cylinder of each pair compresses an air/fuel mixture which is then transferred through a passageway to the second cylinder of the pair. Combustion of the compressed air/fuel mixture takes place within the second cylinder by means of a catalyst within the passageway. The advantage to the engine arrangement taught by Thring is the benefits of fuel injection without the need for a fuel injector, and further the reduction of pollutants within the combustion gases. However, Thring does not directly extract any additional benefit from the combustion gases generated by the cylinder arrangement disclosed.
A second example of intercooperating cylinders is taught in U.S. Pat. No. 2,196,228 to Prescott. Prescott discloses a first cylinder which provides supercharged air to a second cylinder prior to ignition of a combustible mixture in the second cylinder. Following combustion, the first cylinder also acts to assist in exhausting the combustion gases from the second cylinder by being timed such that the first piston lags the second piston, thereby providing an additional exhaust stroke closely timed to the exhaust stroke of the second cylinder. However, the first cylinder is not timed so as to extract any of the energy remaining within the combustion gases of the second cylinder.
Because a substantial amount of the energy generated by an IC engine is lost through the exhausting of the combustion gases, efforts have been made to utilize the hot combustion gases to more completely combust the original air/fuel mixture. An example of this approach is U.S. Pat. No. 4,068,628 which teaches the mixing of additional air with the combustion gases of a majority of an engine's cylinders for purposes of further combustion in a pair of designated exhaust burning cylinders. Another example disclosed in U.S. Pat. No. 4,787,343 the combustion gases to atomize and vaporize the air/fuel mixture prior to injection into the engine's cylinders. However, both of the above U.S. patents are directed towards full combustion of the original air/fuel mixture and neither attempt to directly use the combustion gases alone for deriving additional work from the engine.
From the above discussion of IC engines, it can be readily appreciated that neither the references having intercooperating cylinders nor the references promoting more complete combustion attempt to derive any benefit directly from the enormous energy potential possessed by the combustion gases.
Therefore, it would be desirable to provide an IC engine which derives power directly from the combustion gases for additional power to drive designated pistons of the engine. It would be additionally desirable that such an IC engine provide improved fuel economy while reducing pollutants exhausted into the atmosphere.
Accordingly, what is needed is an IC engine which diverts the combustion gases generated in a first cylinder to a second cylinder for purposes of stroking a piston within the second cylinder, thereby providing additional torque to the crankshaft of the engine.